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3 years ago

Jika x1 dan x2 merupakan akar akar persamaan x2+5x-2=0, maka (x1+2x2)(x2+2x1)=

Mathematics

1 answer:

Anna71 [15]3 years ago

6 0

-8 ........................

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Can you define f(0, 0) = c for some c that extends f(x, y) to be continuous at (0, 0)? If so, for what value of c? If not, expla

Ahat [919]

(i) Yes. Simplify $f(x,y)$ .

$\displaystyle \frac{x^2 - x^2y^2 + y^2}{x^2 + y^2} = 1 - \frac{x^2y^2}{x^2 + y^2}$

Now compute the limit by converting to polar coordinates.

$\displaystyle \lim_{(x,y)\to(0,0)} \frac{x^2y^2}{x^2+y^2} = \lim_{r\to0} \frac{r^4 \cos^2(\theta) \sin^2(\theta)}{r^2} = 0$

This tells us

$\displaystyle \lim_{(x,y)\to(0,0)} f(x,y) = 1$

so we can define $f(0,0)=1$ to make the function continuous at the origin.

Alternatively, we have

$\dfrac{x^2y^2}{x^2+y^2} \le \dfrac{x^4 + 2x^2y^2 + y^4}{x^2 + y^2} = \dfrac{(x^2+y^2)^2}{x^2+y^2} = x^2 + y^2$

and

$\dfrac{x^2y^2}{x^2+y^2} \ge 0 \ge -x^2 - y^2$

Now,

$\displaystyle \lim_{(x,y)\to(0,0)} -(x^2+y^2) = 0$

$\displaystyle \lim_{(x,y)\to(0,0)} (x^2+y^2) = 0$

so by the squeeze theorem,

$\displaystyle 0 \le \lim_{(x,y)\to(0,0)} \frac{x^2y^2}{x^2+y^2} \le 0 \implies \lim_{(x,y)\to(0,0)} \frac{x^2y^2}{x^2+y^2} = 0$

and $f(x,y)$ approaches 1 as we approach the origin.

(ii) No. Expand the fraction.

$\displaystyle \frac{x^2 + y^3}{xy} = \frac xy + \frac{y^2}x$

$f(0,y)$ and $f(x,0)$ are undefined, so there is no way to make $f(x,y)$ continuous at (0, 0).

(iii) No. Similarly,

$\dfrac{x^2 + y}y = \dfrac{x^2}y + 1$

is undefined when $y=0$ .

5 0

1 year ago

use the slope formula to determine the slope of a line that passes through the points (4,9) and (-8,-6)

larisa86 [58]

$\frac{-6-9}{-8-4}\\ \\\frac{-15}{-12}\\ \\= \frac{5}{4}$

Slope: 5/4

6 0

3 years ago

Fill in the missing value in each equation:<br>a)0.25+_____=0<br>b)-5×_____=-5<br>c)_____×-6=0

Mashutka [201]

Answer:

a) -0.25

b) 1

c)0

Step-by-step explanation:

a) 0.25 + (-0.25)=0

b) -5*1=-5

c) 0*(-6)=0

8 0

2 years ago

Geometry one help please!

12345 [234]

What is the question?

3 0

3 years ago

√3×sinx+cosx=0 tmf nghiệm

Crazy boy [7]

Answer:

x= -30

Step-by-step explanation:

√3×sinx+cosx=0

√3sinx=-cosx

√3sinx/-cosx=1

-sinx/cosx=1/√3

-tanx=1/√3

(tan(180-30))=1/√3

tan(-30)=1/√3

Therefore, x= -30

7 0

2 years ago